Apparatus for inspecting substrate and method thereof

ABSTRACT

A substrate inspection apparatus is disclosed. The substrate inspection apparatus includes: a first light source configured to radiate an ultraviolet light onto a coated film of a substrate, the coated film being mixed with fluorescent pigments; a first light detector configured to capture fluorescence generated from the coated film onto which the ultraviolet light is radiated, and to obtain a two-dimensional (2D) image of the substrate; a processor configured to derive one region among a plurality of regions of the substrate based on the 2D image; a second light source configured to radiate a laser light onto the one region; and a second light detector configured to obtain optical interference data generated from the one region by the laser light, wherein the processor is configured to derive a thickness of the coated film of the one region based on the optical interference data.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of U.S. patentapplication Ser. No. 16/202,450, filed Nov. 28, 2018 (now pending), thedisclosure of which is herein incorporated by reference in its entirety.The U.S. patent application Ser. No. 16/202,450 claims priority toKorean Application Nos. 10-2017-0160680 filed on Nov. 28, 2017, and10-2018-0136165 filed on Nov. 7, 2018, respectively, the entire contentsof which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a substrate inspection apparatus and asubstrate inspection method.

BACKGROUND

In a substrate-processing process, a substrate may be coated in order toprotect elements on the substrate. The coating process is referred to asconformal coating. The thickness of a conformal coated film may beinspected in order to check whether the coated film formed on thesubstrate by coating is evenly coated to have a certain thickness.

For inspecting a thickness of the coated film, a two-dimensional (2D)photographic inspection may be performed. The 2D photographic inspectionmay inspect an object by obtaining a 2D image of the object, and 2Dfluorescent photographic inspection may be included therein. The 2Dphotographic inspection performs only qualitative inspection on thethickness of the coated film, and may not accurately measure thethickness of the coated film. Also, it may be difficult to use 2Dphotographic inspection to measure a thickness when the coated film isthin (e.g., about 30 μm).

Further, in order to inspect the thickness of the coated film, aconfocal microscope may be used. However, it takes a long time tomeasure the thickness of the coated film using the confocal microscope.Also, in order to inspect the thickness of the coated film, thethickness may be measured using optical coherence tomography (OCT).However, the measurement using OCT is limited in improving both a depthresolution and a depth measurement range. Saturation due to the lightused in OCT may occur at an electrode part of elements on the substrate,and thus accurate measurement may be difficult.

SUMMARY

Some embodiments of the present disclosure provide a technology formeasuring a thickness of a coated film of a substrate.

In accordance with an aspect of the present disclosure, there isprovided a substrate inspection apparatus. The substrate inspectionapparatus according to an aspect of the present disclosure may include:a first light source configured to radiate an ultraviolet light onto acoated film of a substrate, the coated film being mixed with fluorescentpigments; a first light detector configured to capture fluorescencegenerated from the coated film onto which the ultraviolet light isradiated, and to obtain a two-dimensional (2D) image of the substrate; aprocessor configured to derive one region among a plurality of regionsof the substrate based on the 2D image; a second light source configuredto radiate a laser light onto the one region; and a second lightdetector configured to obtain optical interference data generated fromthe one region by the laser light, wherein the processor may beconfigured to derive a thickness of the coated film of the one regionbased on the optical interference data.

According to an embodiment, the processor may be configured to derive anamount of spread of the coated film for each of the plurality of regionsbased on the 2D image; and to determine, as the one region, a region ofwhich the amount of spread is less than or equal to a predeterminedamount of spread from among the plurality of regions.

According to an embodiment, the substrate inspection apparatus mayfurther include a memory storing information about a region of interestpredetermined by a user, wherein the processor may be configured todetermine the one region based on the information about the region ofinterest.

According to an embodiment, the region of interest may be a regionincluding electrodes of elements on the substrate.

According to an embodiment, the processor may be configured todetermine, as the one region, a region which is identified as a regionincluding a defect on the substrate based on the 2D image.

According to an embodiment, the memory may further store elementarrangement information indicating arrangement of the elements on thesubstrate, and the processor may be configured to derive a regionincluding the electrodes using the element arrangement information.

According to an embodiment, a reflected light which is reflected from asurface of the coated film may be used as a reference light.

According to an embodiment, the processor may be configured to obtain asectional image showing a section cut in a first axial directioncorresponding to a depth direction of the coated film, based on theoptical interference data; and to determine the thickness of the coatedfilm of the one region based on a boundary line in the sectional image.

According to an embodiment, a reflectivity of the surface of the coatedfilm with respect to the laser light may be determined based on afluorescent pigment mixing ratio of the coated film with which thefluorescent pigments are mixed, and the fluorescent pigment mixing ratiomay be set to a value that enables the reflectivity to exceed apredetermined reference value.

According to an embodiment, the coated film may be formed of at leastone material selected from among acrylic, urethane, polyurethane,silicone, epoxy, an ultraviolet (UV) curable material, and an infrared(IR) curable material.

According to an embodiment, the surface of the coated film may be formedto be a curved surface.

In accordance with an aspect of the present disclosure, there isprovided a substrate inspection method. The substrate inspection methodaccording to an aspect of the present disclosure may include the stepsof: radiating an ultraviolet light onto a coated film of a substrate,the coated film being mixed with fluorescent pigments; obtaining a 2Dimage of the substrate by capturing fluorescence generated from thecoated film onto which the ultraviolet light is radiated; deriving oneregion from among a plurality of regions of the substrate based on the2D image; radiating a laser light onto the one region and obtainingoptical interference data generated from the one region by the laserlight; and deriving a thickness of the coated film of the one regionbased on the optical interference data.

According to an embodiment, the step of deriving the one region mayinclude: deriving an amount of spread of the coated film for each of theplurality of regions based on the 2D image; and determining, as the oneregion, a region of which the amount of spread is less than or equal toa predetermined amount of spread from among the plurality of regions.

According to an embodiment, the step of deriving the one region mayinclude determining the one region based on information about a regionof interest predetermined by a user.

According to an embodiment, the region of interest may be a regionincluding electrodes of elements on the substrate.

According to an embodiment, the step of deriving the one region mayinclude determining, as the one region, a region which is identified asa region including a defect on the substrate based on thetwo-dimensional image.

According to an embodiment, the region including the electrodes may bederived based on element arrangement information indicating arrangementof the elements on the substrate.

According to an embodiment, a reflected light which is reflected from asurface of the coated film may be used as a reference light.

According to an embodiment, the step of deriving the thickness of thecoated film of the one region may include: obtaining a sectional imageshowing a section cut in a first axial direction corresponding to adepth direction of the coated film, based on the optical interferencedata; and determining the thickness of the coated film of the one regionbased on a boundary line in the sectional image.

According to an embodiment, a reflectivity of the surface of the coatedfilm with respect to the laser light may be determined based on afluorescent pigment mixing ratio of the coated film with which thefluorescent pigments are mixed, and the fluorescent pigment mixing ratiomay be set to a value that enables the reflectivity to exceed apredetermined reference value.

According to an embodiment, the coated film may be formed of at leastone material selected from among acrylic, urethane, polyurethane,silicone, epoxy, an UV curable material, and an IR curable material.

According to an embodiment, the surface of the coated film may be formedto be a curved surface.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the presentdisclosure, and together with the general description given above andthe detailed description of the embodiments given below, serve toexplain the principles of the present disclosure.

FIG. 1 is a diagram illustrating an embodiment of a process in which asubstrate inspection apparatus according to the present disclosureoperates.

FIG. 2 is a block diagram illustrating an inspection apparatus accordingto various embodiments of the present disclosure;

FIG. 3 is a diagram illustrating a process in which an inspectionapparatus derives an optical coherence tomography (OCT) measurementtarget region based on an element arrangement, according to anembodiment of the present disclosure.

FIG. 4 is a diagram illustrating a process in which an inspectionapparatus derives the OCT measurement target region based on a defectiveregion, according to an embodiment of the present disclosure.

FIG. 5 is a diagram illustrating a process in which an inspectionapparatus additionally measures a region adjacent to the derived OCTmeasurement target region, according to an embodiment of the presentdisclosure.

FIG. 6 is a diagram illustrating a first OCT part according to anembodiment of the present disclosure.

FIG. 7 is a diagram illustrating a second OCT part according to anembodiment of the present disclosure.

FIG. 8 is a diagram illustrating a sectional image and a boundary linein the sectional image according to an embodiment of the presentdisclosure.

FIG. 9 is a diagram illustrating measurement ranges of the first OCTpart and the second OCT part according to an embodiment of the presentdisclosure.

FIG. 10 is a diagram illustrating an embodiment of a substrateinspection method, which may be performed by an inspection apparatusaccording to the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments, examples ofwhich are illustrated in the accompanying drawings. In the followingdetailed description, numerous specific details are set forth in orderto provide a thorough understanding of the present disclosure. However,it will be apparent to one of ordinary skill in the art that the presentdisclosure may be practiced without these specific details. In otherinstances, well-known methods, procedures, systems, and components havenot been described in detail so as not to unnecessarily obscure aspectsof the various embodiments. Various embodiments disclosed in the presentdocument are illustrated for the purpose of accurate description of thetechnical idea of the present disclosure, which should not be construedto be limited to a predetermined embodiment. The technical idea of thepresent disclosure may include various modifications, equivalents,alternatives of the embodiments provided in the present document, andmay include a combination of embodiments selected from some or all ofthe embodiments. Also, the scope of rights of the technical idea of thepresent disclosure is not limited to various embodiments provided belowor to the detailed descriptions thereof.

The terms used in the present document, including technical orscientific terms, have meanings which are generally understood by thoseskilled in the art that the present disclosure belongs to, unlessotherwise defined.

The expressions such as “comprise”, “may comprise”, “include”, “mayinclude”, “have”, “may have”, and the like, used in the presentdocument, indicate that a feature (e.g., a function, an operation, anelement, or the like), which is the object of the expression, exists,and do not exclude other additional features. That is, the expressionsshould be understood as open-ended terms including the possibility thatanother embodiment exists.

In the present document, an expression in the singular form may includethe meaning of the plural form, unless otherwise specified, and thiswill be equally applied to an expression in the singular form includedin the claims.

The expressions such as “1^(st)”, “2^(nd)”, “first”, “second”, and thelike, used in the present document are used to distinguish one objectfrom another object when designating a plurality of objects of the samekind, unless otherwise specified, and the expressions may not define theorder of the objects or the importance of the objects.

The expressions such as “A, B, and C”, “A, B, or C”, “A, B, and/or C”,“at least one of A, B, and C”, “at least one of A, B, or C”, “at leastone of A, B, and/or C”, and the like indicate listed items or allpossible combinations of listed items. For example, “at least one of Aor B” indicates (1) at least one A, (2) at least one B, or (3) at leastone A and at least one B.

The expression “based on” used in the present document is used todescribe one or more factors that affect determination, an operation ofmaking a decision, or an operation described in a phrase or a sentenceincluding the corresponding expression, and the expression does notexclude additional factors that affect the corresponding determination,the operation of making a decision, or the other operation.

In the present document, the expression “an element (e.g., a firstelement) is connected or accessed to another element (e.g., a secondelement)” may indicate that the element is directly connected or linkedto the other element, or may indicate that the element is connected orlinked to the other element using a new element (e.g., a third element)as a medium.

The expression “configured to” used in the present document may includemeanings, such as “set to”, “has an ability to”, “changed so as to”,“made to”, “able to”, and the like. The expression is not limited to“designed specially in terms of hardware.” For example, a processorconfigured to perform a predetermined operation may be a general-purposeprocessor that is capable of performing the predetermined operation byexecuting software.

To describe various embodiments of the present disclosure, an orthogonalcoordinate system may be defined, the system including the x-axis, they-axis, and the z-axis, which are orthogonal to each other. Theexpressions used in the present document, such as “x-axis direction”,“y-axis direction”, “z-axis direction”, and the like in association withthe orthogonal coordinate system, may indicate both directions in whicheach axis in the orthogonal coordinate system extends, unless otherwisespecified. Also, the “+” sign put in front of the direction of each axisindicates the positive direction, which is one of the directions inwhich the corresponding axis extends. The “−” sign put in front of thedirection of each axis indicates the negative direction, which is theother of the directions in which the corresponding axis extends.

In the present disclosure, a substrate is a board or a container inwhich elements such as a semiconductor chip and the like are installed,and the substrate may act as a passageway of electric signals amongelements. The substrate may be used to manufacture an integrated circuitor the like, and may be formed of a material such as silicone or thelike. For example, the substrate may be a printed circuit board (PCB),and may be referred to as a wafer or the like depending on theembodiment.

In the present disclosure, a coated film may be a thin film, which isgenerated on the substrate by coating in order to protect the elementsinstalled on the substrate. When the coated film is thick, the film maybe broken and may affect the operation of the substrate. Accordingly,the coated film needs to be coated relatively thinly and evenly in orderto prevent the coated film from breaking. According to an embodiment,the coated film may be formed of at least one material selected fromamong acrylic, urethane, polyurethane, silicone, epoxy, an ultraviolet(UV) curable material, and an infrared (IR) curable material. In thecase of the coated film formed of at least one of the above-describedmaterials, the reflectivity of the surface of the coated film and/or thebackscattering ratio of the coated film may be higher than those ofother coated films.

In the present disclosure, an optical coherence tomography (OCT) is animaging technology that captures an image of the inside of an objectusing optical interference. Using the OCT, an image showing the insideof an object in the depth direction from the surface of the object maybe obtained. Generally, the OCT is based on an interferometer. The depthresolution with respect to the object may be different depending on thewavelength of the light that is used. The OCT may obtain an image bymore deeply penetrating the object than a confocal microscope, which isanother optical technology.

Hereinafter, various embodiments of the present disclosure will bedescribed with reference to attached drawings. In the drawings anddescriptions of the drawings, the same or substantially equivalentelements may be assigned the same reference numeral. Also, in variousembodiments described below, overlapping descriptions of the sameelements or corresponding elements may be omitted. However, this doesnot mean that an element for which a description is omitted is notincluded in the corresponding embodiment.

FIG. 1 is a diagram illustrating an embodiment of the process by which asubstrate inspection apparatus according to the present disclosureoperates. The substrate inspection apparatus according to the presentdisclosure may be implemented by an inspection apparatus 10 according tovarious embodiments. The inspection apparatus 10 according to variousembodiments of the present disclosure may measure the thickness of acoated film spread on a substrate. According to an embodiment, theinspection apparatus 10 may perform photographic inspection of theentirety of the substrate, using fluorescent pigments, may derive apredetermined region based on a predetermined reference, and mayadditionally measure the thickness of the derived region using the OCT.

First, the inspection apparatus 10 may perform the photographicinspection of a substrate 2 using fluorescent pigments. The photographicinspection may be a fluorescent photographic inspection. To this end,the coated film to be spread on the substrate 2 may be mixed withfluorescent pigments in advance. A first light source 130 of theinspection apparatus 10 may radiate ultraviolet light onto the coatedfilm of the substrate. The radiated ultraviolet light may excitefluorescent pigments mixed in the coated film so as to generatefluorescence. A first light detector 140 of the inspection apparatus 10may capture the fluorescence and obtain a two-dimensional (2D) image ofthe coated film of the substrate 2. The 2D image may be a 2D fluorescentimage, depending on the embodiment.

The inspection apparatus 10 may derive one or more regions 3 of thesubstrate 2 according to a predetermined reference based on the resultof the photographic inspection. According to an embodiment, theinspection apparatus 10 may derive the amount of spread of the coatedfilm for each region of the substrate 2, from the 2D image, and mayderive a predetermined region 3 based on the derived amount of spread.According to an embodiment, the 2D image may show an element installedon the substrate 2 and features or defects of the element on thesubstrate that were generated in the course of performing variousprocesses. The inspection apparatus 10 may derive the predeterminedregion 3 based thereon.

Subsequently, the inspection apparatus 10 may additionally measure thethickness of the derived region 3 using the OCT. An OCT part 170 of theinspection apparatus 10 may obtain optical interference data about thederived region 3, and may additionally measure the thickness of thecoated film spread on the corresponding region 3 on the substrate basedon the obtained optical interference data.

According to an embodiment, the inspection apparatus 10 may derive, fromthe 2D image, an important region, which needs to be protected with thecoated film, on the substrate 2. The important region that needs to beprotected with the coated film may be, for example, a region includingthe electrode part of a component. The important region may be derivedby comparing information stored in advance on a memory with the 2Dimage. The inspection apparatus 10 may additionally measure thethickness of the derived important region using the OCT.

According to an embodiment, the inspection apparatus 10 may measure thethickness of a region of interest predetermined by a user using the OCTpart 170. The memory of the inspection apparatus 10 may storeinformation about the region of interest predetermined by the user.Based on the information, a processor of the inspection apparatus 10 maydetermine a region corresponding to the region of interest as a regionof which the thickness is to be measured using the OCT. According to anembodiment, the region of interest may be a region including theelectrode part of a component or an element as described above.According to an embodiment, the process of deriving a part correspondingto the region of interest may be performed using the 2D image of thesubstrate.

In the present disclosure, the optical interference data may indicatedata obtained from interference light that is generated by interferencebetween measurement light and reference light in the object measurementaccording to the OCT. The measurement light is the light that isradiated and reflected from the object, and the reference light is thelight that is radiated and is reflected from a reference mirror or thelike. An interference phenomenon may occur by a difference in thefeatures (optical path, wavelength, or the like) of the measurementlight and the reference light; a light detector may capture theinterference phenomenon and may obtain the optical interference data.Also, based on the optical interference data, a sectional image showinga section cut in the depth direction of the coated film may begenerated. The optical interference data may also be referred to as aninterference signal.

According to various embodiments of the present disclosure, theinspection apparatus 10 may accurately measure the thickness of thecoated film using the OCT part 170. Also, even when the thickness of thecoated film is less than or equal to, for example, about 30 nm, theinspection apparatus 10 is capable of measuring the thickness of thecoated film.

According to various embodiments of the present disclosure, theinspection apparatus 10 may derive the amount of spread of the coatedfilm for each region of the substrate 2 from the 2D image of thesubstrate 2, may sample a predetermined region according to apredetermined reference, and may additionally measure the thickness ofthe predetermined region using the OCT part 170. Therefore, theinspection apparatus 10 may be capable of accurately measuring thethickness, unlike the 2D photographic inspection, and may also becapable of reducing the amount of time spent for measurement whencompared to the amount of time spent measuring the thickness of thecoated film of the entire substrate using the OCT.

FIG. 2 is a block diagram of the inspection apparatus 10 according tovarious embodiments of the present disclosure. The substrate inspectionapparatus according to the present disclosure may be implemented as theinspection apparatus 10. According to an embodiment, the inspectionapparatus 10 may include the first light source 130, the first lightdetector 140, a second light source 150, a second light detector 160, aprocessor 110, and/or a memory 120. According to an embodiment, at leastone of the elements of the inspection apparatus 10 may be omitted, orother elements may be further added to the inspection apparatus 10.According to an embodiment, additionally or alternatively, some of theelements may be implemented so as to be integrated, or may beimplemented as a single or a plurality of entities.

At least some of the elements disposed in the interior or the exteriorof the inspection apparatus 10 may be connected via a bus, a generalpurpose input/output (GPIO) interface, a serial peripheral interface(SPI), or a mobile industry processor interface (MIPI), or the like, andmay exchange data and/or signals therebetween.

The first light source 130 may radiate the ultraviolet light onto thecoated film of the substrate 2, the coated film being mixed withfluorescent pigment. The first light source 130 may be disposed so as toradiate the ultraviolet light onto the substrate. The relative positionof the first light source 130 on the substrate, the radiation angle ofthe ultraviolet light, the brightness of the ultraviolet light, and thelike may be variously configured. According to an embodiment, theinspection apparatus 10 may include a plurality of first light sources130.

The first light detector 140 may capture fluorescence generated from thecoated film of the substrate 2 by the radiated ultraviolet light.Particularly, when the fluorescent pigments mixed in the coated film areexcited by the radiated ultraviolet light, fluorescence may begenerated. The first light detector 140 may capture the fluorescence andmay obtain a 2D image of the coated film of the substrate 2. Accordingto an embodiment, the inspection apparatus 10 may include a plurality offirst light detectors 140. The first light detector 140 may beimplemented as a charge-coupled device (CCD) or a complementarymetal-oxide-semiconductor (CMOS).

The processor 110 may control at least one element of the inspectionapparatus 10 connected to the processor 110 by driving software (e.g., aprogram). Also, the processor 110 may perform various operations,processing, data generation, and other processes in association with thepresent disclosure. Further, the processor 110 may load data or the likefrom the memory 120, or may store data or the like in the memory 120.

The processor 110 may derive one region among a plurality of regions ofthe substrate 2 based on the 2D image obtained by the first lightdetector 140. The one region may be derived based on a predeterminedreference. The substrate 2 may be divided into a plurality of regions.The plurality of regions may be regions for virtually dividing thesurface of the substrate 2, which may be divided in advance based on apredetermined reference.

According to an embodiment, the processor 110 may derive the amount ofspread of the coated film for each of the plurality of regions of thesubstrate 2, and may derive the above-described one region based on theamount of spread. Particularly, the processor 110 may obtain luminanceinformation for each of the plurality of regions of the substrate 2 fromthe obtained 2D image. In the present disclosure, the luminance mayindicate the intensity of light per unit area of a light source or asurface that reflects light, that is, the amount of light emitted perunit area. The luminance information of one region may be informationindicating the luminance of the fluorescence generated from the region.The processor 110 may derive the amount of spread of the coated film foreach of the plurality of areas of the substrate 2 based on the obtainedluminance information. The coated film of the substrate 2 may includefeatures, such as unevenness, a curve, or the like, depending onelements existing on the substrate 2, a predetermined feature or defecton the substrate 2, or the degree of evenness of the coated film.According to the features of the substrate 2, such as the unevenness,the curve or the like, the amount of fluorescent pigments spread on eachregion of the coated film may be different. When the ultraviolet lightis radiated, the luminance of each region of the coated film may bedifferent depending on the amount of fluorescent pigments. The processor110 may derive the amount of spread of the coated film for each regionusing the luminance of each region. The processor 110 may derive aregion (e.g., a first region), of which the amount of spread of thecoated film is less than or equal to a predetermined amount of spread,from among the plurality of regions of the substrate 2. Thepredetermined amount of spread may be determined based on the intentionof a designer, and the information thereon may be stored on the memory120.

The processor 110 may measure the thickness of the coated film of thederived region (e.g., the first region) by controlling the OCT part 170.The processor 110 may obtain optical interference data (e.g., firstoptical interference data) associated with interference light generatedfrom the derived region (e.g., the first region). The processor 110 mayderive the thickness of the coated film of the derived region (e.g., thefirst region) using the obtained optical interference data (e.g., thefirst optical interference data).

The OCT part 170 may include the second light source 150 and/or thesecond light detector 160. Particularly, the processor 110 may performthe above-described operation by controlling the second light source 150and the second light detector 160. The OCT part 170 may be implementedas one of the various types described below.

The second light source 150 may radiate laser light onto the coated filmof the substrate 2. The disposition of the second light source 150, therelative position of the second light source 150 on the substrate andthe like may be variously configured, and may be differently configureddepending on the type of the OCT part 170. According to an embodiment,the second light source 150 may use a laser of which the wavelength isvariable within a short time, whereby optical interference datacorresponding to different wavelengths may be obtained using the same.According to an embodiment, the inspection apparatus 10 may include aplurality of second light sources 150. The second light source 150 maybe controlled by the processor 110 and may radiate laser light onto theabove-described derived region (e.g., the first region or the like).

The second light detector 160 may capture interference light generatedfrom the coated film by the laser light. Particularly, when a first OCTpart, which will be described below, is used, the second light detector160 may capture the interference light generated by reflected light(reference light), which is laser light reflected from a referencemirror, and measurement light reflected from the coated film. A sectionimage for a reference mirror surface may be generated using the opticalinterference data obtained by capturing the interference light. When asecond OCT part, which will be described below, is used according to anembodiment, the second light detector 160 may capture the interferencelight generated by the reflected light and the scattered light. Thereflected light is the laser light reflected from the surface of thecoated film, and the scattered light is the laser light that penetratesthe coated film to a predetermined depth and is backscattered. Here, thereflected light that is reflected from the surface of the coated filmacts as reference light, and the scattered light acts as measurementlight. A section image based on a coated film surface may be generatedusing the optical interference data obtained by capturing theinterference light. According to an embodiment, the inspection apparatus10 may include a plurality of second light detectors 160. The secondlight detector 160 may be implemented as the CCD or the CMOS. The secondlight detector 160 may be controlled by the processor 110 and may obtainthe optical interference data (e.g., the first optical interference dataor the like) associated with reference light generated from theabove-described derived region (e.g., the first region or the like) bythe laser light.

The memory 120 may store various data. The data stored on the memory 120may be data obtained, processed, or used by at least one element of theinspection apparatus 10, and may include software (e.g., a program). Thememory 120 may include a transitory memory and/or a non-transitorymemory. The memory 120 may store data obtained from the first lightdetector 140 and the second light detector 160. Also, the memory 120 maystore the luminance information of each region of the substrate 2,derived from the 2D image, and/or coated film thickness informationderived by the processor 110. Further, the memory 120 may store, inadvance, element arrangement information 1000, element densityinformation 2000, features of elements on a substrate, information abouta defective region, electrode position information 3000 about theposition of an electrode on a substrate, information about the region ofinterest set in advance by a user, and the like.

In the present disclosure, the element arrangement information 1000 maybe information indicating the arrangement of elements disposed on thesubstrate 2. The element arrangement information 1000 may indicateinformation about positions and orientations of the elements installedon the substrate 2 and the areas occupied thereby. The elementarrangement information 1000 may be used as a basis to adjust theabove-described luminance information or to specify a predeterminedregion on the substrate. According to an embodiment, the inspectionapparatus 10 may derive the amount of spread of the coated film for eachof the plurality of regions of the substrate, based on the elementarrangement information and the 2D image.

In the present disclosure, the element density information 2000 may beinformation indicating the density of the elements disposed on thesubstrate 2. The element density information 2000 may indicate thedensity of elements or the like in each region of the substrate 2 bytaking into consideration the ratio of the area that an object occupiesto a unit area, such an object including an element, the electrode of anelement, a solder ball, a metallic wire, a lead frame, and the like. Theelement density information 2000 may be derived based on the elementarrangement information 1000.

In the present disclosure, a program may be software stored on thememory, and may include an operating system for controlling resources ofthe inspection apparatus, applications, and/or middleware that providesvarious functions to the applications such that the applications utilizethe resources of the inspection apparatus.

According to an embodiment, the inspection apparatus 10 may furtherinclude a communication interface (not illustrated). The communicationinterface may enable wired or wireless communication between theinspection apparatus 10 and other servers or between the inspectionapparatus 10 and an external electronic device. For example, thecommunication interface may perform the wireless communication based onlong-term evolution (LTE), LIE Advanced (LTE-A), code division multipleaccess (CDMA), wideband CDMA (WCDMA), wireless broadband (WiBro), Wi-Fi,Bluetooth, nearfield communication (NFC), global positioning system(GPS) or global navigation satellite system (GNSS), or the like. Forexample, the communication interface may perform the wired communicationbased on a universal serial bus (USB), a high-definition multimediainterface (HDMI), recommended standard 232 (RS-232), a plain oldtelephone service (POTS), or the like.

According to an embodiment, the processor 110 may obtain informationfrom a server by controlling the communication interface. Theinformation obtained from the server may be stored on the memory 120.According to an embodiment, the information obtained from the server mayinclude the element arrangement information 1000, the element densityinformation 2000, the features of elements on the substrate, theinformation about the defective region, the electrode positioninformation 3000 about the position of an electrode on a substrate, theinformation about the region of interest set in advance by a user, andthe like.

According to an embodiment, the inspection apparatus 10 may furtherinclude an input device (not illustrated). The input device may be adevice that receives, from the outside, data which is to be transferredto at least one element of the inspection apparatus 10. The input devicemay receive, from a user, information about the region of interest. Forexample, the input device may include a mouse, a keyboard, a touch pad,or the like.

According to an embodiment, the inspection apparatus 10 may furtherinclude an output device (not illustrated). The output device may be adevice that provides various data, such as an inspection result, anoperation state, and the like of the inspection apparatus 10 to a userin a visual form. For example, the output device may include a display,a projector, a hologram, or the like.

According to an embodiment, the inspection apparatus 10 may be providedin one of the various types of devices. For example, the inspectionapparatus may be a portable communication device, a computer device, aportable multimedia device, or a wearable device, or may be acombination of one or more of the above-described devices. Theinspection apparatus of the present disclosure is not limited to theabove-described devices.

Various embodiments of the inspection apparatus 10 according to thepresent disclosure may be applied in combination. Many combinations ofthe embodiments as the possible number of cases may exist, and theembodiments of the inspection apparatus 10 resulting from suchcombination may also be included in the scope of the present disclosure.Also, the elements disposed in the interior or the exterior of theinspection apparatus 10 according to the present disclosure may beadded, modified, replaced, or removed depending on the embodiment. Also,the elements disposed in the interior or the exterior of the inspectionapparatus 10 may be implemented as hardware components.

FIG. 3 is a diagram illustrating a process in which the inspectionapparatus 10 derives an OCT measurement target region based on elementarrangement according to an embodiment of the present disclosure.According to an embodiment, the processor 110 may derive a region (e.g.,a second region), of which the arrangement of elements is the same as,or similar to, that of a region (e.g., a first region) of which theamount of spread derived from a 2D image is less than or equal to apredetermined amount of spread. Further, the processor 110 may derivethe thickness of the derived region (e.g., the second region) bycontrolling the OCT part 170. In other words, the processor 110 mayderive a region having the same or similar element arrangement based onthe element arrangement information 1000, and may measure the thicknessof the region using the OCT.

The region having the same or similar element arrangement may have athickness similar to that of a coated film. When it is determined thatthe amount of spread on one region is less than or equal to apredetermined amount of spread via inspection using a 2D image, anotherregion that has an element arrangement the same as or similar to that ofthe one region may have an amount of spread of the coated film that issimilar to that of the one region. Accordingly, in order to improve theaccuracy of the entire coated film thickness inspection, the inspectionapparatus 10 may further perform an operation according to the presentembodiment.

The processor 110 may derive a region 3 (e.g., the first region) ofwhich the amount of spread obtained via the 2D image is less than orequal to a predetermined amount of spread, as described above. Accordingto an embodiment, the processor 110 may measure the thickness of theregion 3 using the OCT part 170.

In addition, the processor 110 may derive a region 4 that has the sameelement arrangement as that of the derived region 3 on the substrate 2.The region 4 (e.g., the second region) may be selected from amongregions (regions excluding the first region) of which the amount ofspread derived from the 2D image exceeds the predetermined amount ofspread. The processor 110 may derive the corresponding region 4 based onthe above-described element arrangement information 1000.

The processor 110 may derive the thickness of the additionally derivedregion 4 using the OCT part 170. The processor 110 may control thesecond light source 150 and the second light detector 160 so as toobtain optical interference data (e.g., second optical interferencedata) generated by laser light reflected from the corresponding region4. The processor 110 may derive the thickness of the coated film spreadon the region 4 based on the obtained optical interference data. In thepresent disclosure, the fact that the processor 110 obtains opticalinterference data of one region by controlling the second light source150 and the second light detector 160 may indicate that the second lightsource 150 radiates laser light onto the corresponding one region andthat the second light detector 160 obtains optical interference dataassociated with interference light generated from the one region.

According to an embodiment, the processor 110 may derive the region 4,of which the element arrangement is similar to that of the region 3derived from the 2D image. Further, the processor 110 may measure thethickness of the region 4 using the OCT. Here, whether the elementarrangements of the two regions 3 and 4 are similar to each other may bedetermined based on the element arrangement information 1000 about thetwo regions 3 and 4. The processor 110 may calculate the similarity ofthe element arrangements of the two regions based on the areas that theelements occupy in the regions 3 and 4, the arrangements, the type, andthe form of the elements, the positions of electrodes of the elements,or the like. Further, the processor 110 may determine whether theelement arrangements of the two regions are similar to each other basedon the calculated similarity.

According to an embodiment, the processor 110 may adjust theabove-described luminance information based on the density of elementsand an element arrangement on the substrate 2, and may derive the amountof spread of the coated film of a corresponding region based on theadjusted luminance information. Particularly, the processor 110 mayobtain the element arrangement information 1000 indicating thearrangement of elements on the substrate 2 from the memory 120. Theprocessor 110 may derive the element density information 2000 about eachregion on the substrate 2 based on the above-described elementarrangement information 1000. The processor 110 may adjust luminanceinformation derived from the 2D image based on the element densityinformation 2000. The fluorescent pigments may not be evenly spread on aregion having a high element density in the substrate 2. In regions witha high element density, that is, regions in which elements are denselydisposed, fluorescent pigments may be accumulated, and thus luminancemay be measured to be high. The processor 110 may adjust the obtainedluminance information by taking into consideration luminance distortionby the element density. To adjust the luminance information, accumulatedinformation indicating the relationship between element density andluminance may be used. The information may be collected in a databaseand may be stored on the memory 120. The processor 110 may derive theamount of spread on each region of the substrate 2 based on the adjustedluminance information.

FIG. 4 is a diagram illustrating the process by which the inspectionapparatus 10 derives an OCT measurement target region based on adefective region, according to an embodiment of the present disclosure.According to an embodiment, the processor 110 may derive a region 5(e.g., a third region), which is determined as a region having a defecton the substrate 2 based on the element arrangement information 1000and/or the 2D image, and may derive the thickness of the region 5 (e.g.,the third region) by controlling the OCT part 170.

When the amount of spread on a part including a predetermined defect onthe substrate 2 or a coated film, for example, a part including a crack,an exfoliation, an unevenness, a curve or the like, is measured via 2Dphotographic inspection, the result may include an error. Accordingly,the thickness of the coated film of the region 5, which is determined tobe a region including a predetermined defect based on the elementarrangement information 1000 and/or the 2D image, may be additionallymeasured using the OCT part 170.

The processor 110 may determine the region 5, which is determined to bea region including a predetermined defect on the substrate 2, based onthe element arrangement information 1000 and/or the 2D image obtainedfrom the memory 120. The 2D image may be a picture obtained by actuallyphotographing the form of the substrate 2 and the coated film. Theelement arrangement information 1000 may show the form of the substrate2 and the expected form in which the coated film is spread according toa predetermined specification. The processor 110 may determine a regionin which the current substrate 2 and the coated film have featuresdifferent from the predetermined standard, by comparing the elementarrangement information 1000 with the 2D image. That is, the processor110 may determine that the corresponding feature is a defect. Theprocessor 110 may derive the region 5 where the defect exists.

The processor 110 may derive the thickness of the derived region 5 usingthe OCT part 170. The processor 110 may control the second light source150 and the second light detector 160 so as to obtain opticalinterference data (e.g., third optical interference data) generated bylaser light reflected from the corresponding region 5. The processor 110may derive the thickness of the coated film spread on the correspondingregion 5 based on the obtained optical interference data (e.g., thethird optical interference data).

According to an embodiment, the operation of deriving an additionalmeasurement target region based on a defective region may be performedindependently from the above-described operation of deriving anadditional measurement region based on the 2D image.

Also, according to an embodiment, the processor 110 may derive a region(e.g., a fourth region) including an electrode part based on theelectrode position information 3000 indicating the positions ofelectrodes of elements on the substrate 2, and may additionally measurethe thickness of the region (e.g., the fourth region) by controlling theOCT part 170. In the present disclosure, the electrode positioninformation 3000 may be information indicating the positions of theelectrodes of the elements disposed on the substrate 2. For example,each element may have an electrode part in order to connect fine wiringbetween an element and the substrate. The electrode may be referred toas an element leg or a chip leg. The electrode position information 3000may indicate the positions where the electrodes of elements exist on thesubstrate 2. Generally, at the electrode part of an element, fluorescentpigments may agglomerate by the density of element legs, wherebythickness measurement based on the 2D image may be inaccurate.Accordingly, the thickness of the part where the electrode of an elementexists may be additionally measured using the OCT, whereby the accuracyof the process of measuring the overall thickness may be increased.

The processor 110 may be aware of the positions where the electrodes ofthe elements exist on the substrate 2 based on the electrode positioninformation 3000 obtained from the memory 120. The processor 110 mayderive a region (e.g., the fourth region) where an electrode exists onthe substrate 2. According to an embodiment, the corresponding region(e.g., the fourth region) may be selected from among regions in whichthe amount of spread obtained from the 2D image exceeds a predeterminedamount of spread (i.e., regions excluding the first region).

The processor 110 may measure the thickness of the derived region (e.g.,the fourth region) using the OCT part 170. The processor 110 may controlthe second light source 150 and the second light detector 160 so as toobtain optical interference data (e.g., fourth optical interferencedata) generated by laser light reflected from the corresponding region(e.g., the fourth region). The processor 110 may derive the thickness ofthe coated film spread on the corresponding region (e.g., the fourthregion) based on the obtained optical interference data (e.g., thefourth optical interference data).

FIG. 5 is a diagram illustrating a process in which the inspectionapparatus 10 additionally measures a region adjacent to a derived OCTmeasurement target region according to an embodiment of the presentdisclosure. In the case of regions on the substrate 2 derived accordingto various embodiments of the present disclosure, that is, regions 7 towhich additional thickness measurement is performed using the OCT, theinspection apparatus 10 may additionally measure the thickness of aregion 8 adjacent to the region 7 using the OCT.

The derived regions 7 may be regions where thickness measurement usingthe OCT may be performed in addition to 2D photographic inspection foraccurate coated film thickness measurement. The regions adjacent to theregions 7 may have features similar to those of the regions 7 inassociation with the substrate 2 or the coated film. Accordingly, inorder to secure the accuracy of the overall thickness measurement, theadditional thickness measurement using the OCT may be performed withrespect to the adjacent regions.

Here, the adjacent regions indicate regions located close to thecorresponding region 7 when the substrate 2 is divided into a pluralityof regions. According to an embodiment, the adjacent region may indicatea region that shares a boundary line with the corresponding region 7from among the plurality of regions. According to an embodiment, theadjacent region may indicate a region located within a predeterminedradius from the center of the corresponding region 7, from among theplurality of regions. According to an embodiment, when axescorresponding to the horizontal direction and vertical direction of thesubstrate are the x-axis and y-axis, respectively, the adjacent regionmay be a region that is located in the +x-axis direction, the −x-axisdirection, the +y-axis direction, or the −y-axis direction of thecorresponding region 7 and shares a boundary line with the correspondingregion 7. According to an embodiment, the adjacent region may include aregion that shares a vertex with the corresponding region 7 and islocated in the diagonal direction, from among the plurality of regions.

According to an embodiment, the processor 110 may remeasure a thicknessusing the OCT, based on the amount of spread derived from the 2D imageand a thickness value measured by the OCT part 170. According to anembodiment, when the difference between the thickness value of thecoated film of a corresponding region, which is derived from the amountof spread based on the qualitative analysis, and the thickness valuemeasured using the OCT is greater than or equal to a predeterminedvalue, the thickness of the corresponding region may be remeasured usingthe OCT. Also, according to an embodiment, based on the derived amountof spread and the derived thickness value, when it is determined thatthe amount of spread and the thickness value do not satisfy apredetermined reference, a thickness may be remeasured. Here, thepredetermined reference may be a reference to determine whether at leastone of the derived amount of spread or the derived thickness is wronglymeasured, in consideration of the relationship between the amount ofspread and the thickness that were previously measured. That is, when itis determined that the measurement has an error in consideration of theamount of spread and the thickness value, measurement may be performedagain. Also, according to an embodiment, the processor 110 may controlthe OCT part 170 and may remeasure the thickness of a region adjacent tothe corresponding region, based on the amount of spread of thecorresponding region derived from the 2D image and the thickness valueof the corresponding region measured by the OCT part 170.

FIG. 6 is a diagram illustrating a first OCT part according to anembodiment of the present disclosure. The above-described OCT part 170may be implemented as the first OCT part or a second OCT part accordingto an embodiment.

The first OCT part may further include a beam splitter 171 and areference mirror 172, in addition to the second light source and thesecond light detector. The beam splitter 171 may adjust an optical pathof laser light radiated from the second light source 150, and thereference mirror 172 may reflect the laser light transferred from thebeam splitter 171 so as to generate the reference light. The first OCTpart may be used to obtain optical interference data from interferencelight generated by the interference between measurement light, which islaser light reflected from the coated film of the substrate 2, andreference light, which is laser light reflected from the referencemirror 172.

Particularly, the second light source 150 may radiate the laser light.According to an embodiment, the second light source 150 may directlyradiate the laser light onto the beam splitter 171. According to anembodiment, the second light source 150 may transfer the laser light toa convex lens 173 via an optical fiber 174, and the laser light passingthrough the convex lens 173 may be transferred to the beam splitter 171.

The beam splitter 171 may adjust an optical path such that part of thelaser light received from the second light source 150 passes through thebeam splitter 171 and proceeds to the coated film of the substrate 2,and may adjust an optical path such that another part of the laser lightis reflected and proceeds to the reference mirror 172.

The part of the laser light, of which the optical path is adjusted suchthat the part of the laser light proceeds to the coated film of thesubstrate 2, may be reflected from the coated film of the substrate 2.As described above, the laser light may be reflected from the surface ofthe coated film, or may penetrate to a predetermined depth from thesurface of the coated film and may be backscattered depending on thewavelength of the laser light. The reflected light or scattered lightmay be referred to as measurement light. The measurement light mayproceed to the beam splitter 171, and may be transferred to the secondlight detector 160 by the beam splitter 171.

The other part of the laser light, of which the optical path is adjustedsuch that the other part of the laser light proceeds to the referencemirror 172, may be reflected by the reference mirror 172. The reflectedlight may be referred to as reference light. The reference light maypass through the beam splitter 171, and may be transferred to the secondlight detector 160.

The second light detector 160 may capture interference light generatedby the measurement light and the reference light. The second lightdetector 160 may capture the interference light, and may obtain theoptical interference data (e.g., the first optical interference data).The processor 110 may obtain the optical interference data from thesecond light detector 160, may generate a sectional image of the coatedfilm based on the optical interference data, and may derive thethickness of the coated film spread on a corresponding region of thesubstrate 2.

FIG. 7 is a diagram illustrating a second OCT part according to anembodiment of the present disclosure. The second OCT part may includethe second light source 150 and/or the second light detector 160. Thesecond OCT part may not need the beam splitter 171 and the referencemirror 172. The second OCT part may be used to obtain opticalinterference data from interference light generated by interferencebetween reflected light, which is laser light reflected from the surfaceof the coated film of the substrate 2, and scattered light, which islaser light that passes through the coated film and is backscatteredfrom the boundary between the coated film and the substrate 2 on whichthe coated film is spread. Here, the reflected light reflected from thesurface of the coated film may act as the above-described referencelight, and the scattered light may act as the measurement light.

Particularly, the second light source 150 may radiate laser light ontothe coated film of the substrate 2. In this instance, the laser lightmay be radiated along a first direction. The first direction may be adirection that corresponds to a straight line inclined at apredetermined angle from the direction of a normal line of thesubstrate. According to an embodiment, the first direction may be thesame as the direction of the normal line of the substrate. The axiscorresponding to the direction of the normal line of the substrate isreferred to as the z-axis. The z-axis may be a direction correspondingto the depth direction of the coated film. As described above, thesecond light source 150 may directly radiate the laser light, but mayalternatively radiate the laser light via the optical fiber 174 and/orthe convex lens 173.

The laser light may be reflected from the surface of the coated film.Particularly, the laser light may be reflected from a first side, whichis illustrated in FIG. 7. Further, the laser light may penetrate thecoated film, and may be backscattered from the boundary between thecoated film and the substrate on which the coated film is spread.Particularly, the laser light may be backscattered from a second side,which is illustrated in FIG. 7. The reflected light and scattered lightmay generate the interference light, and the interference light mayproceed in the direction reverse to the above-described first direction.That is, the radiated laser light and the above-described interferencelight may proceed along the same axis but in different respectivedirections. The second light detector 160 may capture the interferencelight that proceeds in the direction opposite to the first direction.The second light detector 160 may obtain optical interference data(e.g., the first optical interference data) from the capturedinterference light. The processor 110 may obtain the opticalinterference data from the second light detector 160, may generate thesectional image based on the optical interference data, and may derivethe thickness of the coated film spread on a corresponding region of thesubstrate 2.

In the case of the thickness measurement using the second OCT part, thereflected light and the scattered light may perform the roles of thereference light and the reflected light of the above-described first OCTpart, respectively. That is, the surface of the coated film itself mayact as the reference mirror 172 of the above-described first OCT part.

According to an embodiment, when the reflectivity of the surface of thecoated film is greater than or equal to a predetermined reference value,an OCT part of a type the same as that of the second OCT part may beused. The predetermined reference value may be the minimum reflectivitythat is needed when the surface of the coated film performs the role ofthe reference mirror 172. According to an embodiment, the radiationangle at which the laser light is to be radiated may be adjusted suchthat the reflectivity of the surface of the coated film is greater thanor equal to a reference value. According to an embodiment, the laserlight may be radiated onto a region where the surface of the coated filmis parallel to the substrate, such that the reflectivity of the surfaceof the coated film is greater than or equal to the reference value. Inthe case of the thickness measurement using the second OCT part of thepresent disclosure, the reflectivity of the surface of the coated filmmay indicate the ratio of reflected light reflected from the surface ofthe coated film to the laser light radiated onto the coated film.

According to an embodiment, the reflectivity of the surface of thecoated film may be determined based on the mixing ratio of fluorescentpigments of the corresponding coated film. According to an embodiment,the surface of a coated film mixed with fluorescent pigments may havehigher reflectivity than that of a coated film that is not mixed withthe fluorescent pigment. As the mixing ratio of fluorescent pigments ofthe coated film increases, the reflectivity of the surface of the coatedfilm may increase. That is, when a coated film mixed with thefluorescent pigments is used, the reflectivity of the surface of thecoated film increases, whereby thickness measurement using the secondOCT part may be easily performed. According to an embodiment, the mixingratio of the fluorescent pigments of the coated film may be set to avalue that enables the reflectivity of the surface of the coated film toexceed a predetermined reference value. According to an embodiment, thereference value may be the minimum reflectivity that is needed when thesurface of the coated film performs the role of the reference mirror172, or may be a value arbitrarily set according to the intention of auser.

According to an embodiment, the backscattering ratio of the coated filmmay also be determined based on the mixing ratio of the fluorescentpigments of the corresponding coated film. According to an embodiment, acoated film mixed with the fluorescent pigments may have a higherbackscattering ratio than that of a coated film that is not mixed withthe fluorescent pigments. In the case of the thickness measurement usingthe second OCT part of the present disclosure, the backscattering ratioof the coated film may indicate the ratio of scattered light that isbackscattered to the laser light radiated onto the coated film. As themixing ratio of the fluorescent pigments of the coated film increases,the backscattering ratio of the coated film may increase. That is, whena coated film mixed with the fluorescent pigments is used, thebackscattering ratio of the coated film increases, whereby thicknessmeasurement using the second OCT part may be easily performed. Accordingto an embodiment, the mixing ratio of the fluorescent pigments of thecoated film may be set to a value that enables the backscattering ratioof the coated film to exceed a predetermined reference value.

According to an embodiment, the surface of the coated film may be formedto be a curved surface. According to an embodiment, the surface of thecoated film may be formed to be a convexly curved surface, a concavelycurved surface, or a curved surface provided in an arbitrary shape forthe substrate. According to an embodiment, in the case in which thesurface of the coated film is a curved surface, the thicknessmeasurement using the second OCT part may be more easily performed thanthe case in which the surface of the coated film is a flat surface.

According to an embodiment, the second OCT part may not dispose anadditional element, such as a window glass or the like, on the coatedfilm of the substrate 2. The second OCT part according to the presentdisclosure uses reflected light, which is reflected from the surface ofthe coated film, as the reference light, and obtains the opticalinterference data. Accordingly, an additional separate element neededfor generating the reference light, such as a window glass or the like,may not be needed.

FIG. 8 is a diagram illustrating a sectional image and a boundary linein the sectional image according to an embodiment of the presentdisclosure. The processor 110 may derive the thickness of the coatedfilm spread on a predetermined region from the obtained opticalinterference data. The processor 110 may generate a sectional image fromthe optical interference data, and may derive the thickness of thecoated film using information obtained from the sectional image.

According to the present disclosure, in an object measurement using theOCT, the sectional image is a 2D image of a section cut in the depthdirection of an object (coated film). The sectional image may begenerated based on the measured optical interference data. The sectionalimage may include boundary lines (boundary patterns) corresponding tothe boundary between air and the coated film and the boundary betweenthe coated film and the substrate.

Particularly, the processor 110 may obtain a sectional image as shown inFIG. 8 using the optical interference data obtained by the second lightdetector 160. The sectional image may be an image showing a section cutin the −z-axis direction, that is, the depth direction, of the substrate2 and the coated film. That is, the sectional image may show the insideof the coated film and the substrate via penetration in the depthdirection from the surface of the coated film.

A sectional image 8010 may be a sectional image that may be obtained bythe above-described first OCT part. The sectional image 8010 may includeone or more boundary lines 8050. Each of the boundary lines 8050 may bethe boundary between air and the coated film, in other words, theboundary line corresponding to the surface of the coated film, or may bethe boundary line corresponding to the boundary between the coated filmand the substrate 2 or an electrode on which the coated film is spread.The processor 110 may derive the thickness of the coated film using thedistance between the boundary lines corresponding to the respectiveboundaries.

Particularly, the sectional image 8010, which is based on a referencemirror surface, may be obtained using the first OCT part. The processor110 may determine a boundary line indicating the boundary between airand the coated film from the sectional image 8010. Also, the processor110 may determine a boundary line indicating the boundary between thecoated film and the substrate 2 on which the coated film is spread fromthe sectional image 8010. The processor 110 may derive a verticaldistance between the two determined boundary lines in the sectionalimage 8010, and may determine the vertical distance as the thickness ofthe coated film. According to an embodiment, the processor 110 may applya predetermined scaling factor to the determined vertical distance, andmay determine the derived value as the thickness of the coated film.

According to an embodiment, the processor 110 may use a predeterminedsegmentation algorithm in order to separate the boundary line indicatingthe boundary between air and the coated film and the boundary lineindicating the boundary between the coated film and the substrate 2among the plurality of boundary lines 8050 in the sectional image 8010.Also, the processor 110 may perform the above-described boundary linesegmentation using accumulated information indicating the relationshipbetween the boundary lines of the sectional image and the boundariesamong air, the coated film and the substrate, which is collected in adatabase and is stored on the memory 120. According to an embodiment,the processor 110 may determine the direction in which boundary lines(boundary patterns) of the sectional image 8010 are to be detected firstfrom among the vertical direction or the horizontal direction, and maydetect a boundary line in the determined direction. According to anembodiment, the processor 110 distinguishes an overlapping boundary linegenerated by multiple reflections, among the detected boundary lines,and may exclude the overlapping boundary line when the thickness ismeasured.

The sectional image 8020, which is based on a surface of the coatedfilm, may be obtained using the second OCT part. The sectional image8020 may include one or more boundary lines 8040. One of the boundarylines 8040 may be a boundary line corresponding to the boundary betweenthe coated film and the substrate 2 or the electrode on which the coatedfilm is spread. The processor 110 may derive the thickness of the coatedfilm using the interval between the corresponding boundary line 8040 andan upper edge 8030 of the sectional image 8020.

Particularly, when the second OCT part is used, the processor 110 maydetect the boundary line 8040 indicating the boundary between the coatedfilm and the substrate 2 on which the coated film is spread. Theprocessor 110 may determine, as the corresponding boundary line 8040,the boundary line that appears first in the depth direction from theupper edge of the sectional image 8020. Also, in the case of the secondOCT part, the optical interference data is generated using the reflectedlight which is reflected from the surface of the coated film.Accordingly, the sectional image may show a section cut in the −z-axisdirection, that is, in the depth direction, from the surface of thecoated film by taking the surface of the coated film as an origin point.Accordingly, the upper edge 8030 of the sectional image 8020 obtained bythe second OCT part may correspond to the surface of the coated film.The processor 110 may derive the vertical distance between the detectedboundary line 8040 and the upper edge 8030 of the sectional image 8020,and may determine the vertical distance as the thickness of the coatedfilm. According to an embodiment, the processor 110 may determine, asthe thickness of the coated film, a value derived by applying apredetermined scaling factor to the derived vertical distance.

According to an embodiment, the thickness measurement of the coated filmof the substrate using the OCT may be performed in a vacuum or in someother medium. That is, laser light radiation of the OCT part 170 andreflected light movement may be performed in a vacuum or another medium,instead of air.

FIG. 9 is a diagram illustrating measurement ranges of the first OCTpart and the second OCT part according to an embodiment of the presentdisclosure. A sectional image 9010 shown in FIG. 9 may be a sectionalimage that may be obtained by the first OCT part. The sectional image9010 may include a boundary line indicating the boundary between air andthe coated film and a boundary line indicating the boundary between thecoated film and the substrate (PCB). Also, a sectional image 9020 shownin FIG. 9 may be a sectional image that may be obtained by the secondOCT part. The sectional image 9020 may include a boundary lineindicating the boundary between the coated film and the substrate (PCB).

According to an embodiment, the sectional image 9010 may be bigger thanthe sectional image 9020. That is, the amount of data of the sectionalimage 9010 may be bigger than that of the sectional image 9020. In thecase of the measurement using the second OCT part, unlike the first OCTpart, the reflected light that is reflected from the surface of thecoated film is used as the reference light, and thus the start of themeasurement range in the depth direction (the −z-axis direction) islimited to the surface of the coated film.

Referring to a sectional diagram 9030 shown in FIG. 9, in the case ofthe thickness measurement of the coated film using the first OCT part, ameasurement range 9040, which takes into consideration all differencesin height among the elements installed on the substrate 2, may be neededin order to obtain a meaningful measurement result. However, in the caseof the thickness measurement of the coated film using the second OCTpart, a meaningful thickness measurement result may be obtained usingonly a measurement range 9050 corresponding to the maximum predictedthickness of the coated film. That is, the inspection apparatus 10 mayreduce a measurement range in the depth direction, which is needed inorder to measure the thickness of the coated film, depending on the typeof the OCT part 170, whereby operational capacity for processing ameasurement result and memory for storage may be reduced.

Also, in the case of the thickness measurement the coated film using thesecond OCT part, the reference mirror 172 is not used, and thus thepossibility of a measurement error by saturation with reflected lightmay be reduced. When the amount of output of radiated light exceeds apredetermined amount of light, the amount of reflected light increases,and thus optical interference data or an interference signal shown inthe sectional image may be saturated. In the case of such saturation, aninterference signal may appear, irrespective of an interference signalgenerated by a measurement object, thereby impeding accuratemeasurement. Such saturation may more frequently occur in the case ofthe first OCT part, which uses the highly reflective reference mirror172. The second OCT part excludes the use of the reference mirror,whereby measurement error by saturation may be reduced.

FIG. 10 is a diagram illustrating an embodiment of a substrateinspection method that may be performed by the inspection apparatus 10according to the present disclosure. Although the flowchart hasdescribed that the operations of a method and an algorithm according tothe present disclosure are performed sequentially, the operations may beperformed in a different order that is arbitrary combined based on thepresent disclosure, in addition to being performed in the sequentialorder. The descriptions associated with the flowchart do not excludemodification or correction of the method or the algorithm, and do notindicate that a predetermined operation is essential or preferable.According to an embodiment, at least some operations may be performed inparallel, repetitively, or heuristically. According to an embodiment, atleast some operations may be omitted, or other operations may be added.

The inspection apparatus 10 according to the present disclosure mayperform a substrate inspection method according to various embodimentsof the present disclosure in order to perform a substrate inspection.The substrate inspection method according to an embodiment of thepresent disclosure may include: a step S100 of radiating ultravioletlight onto a coated film of a substrate; a step S200 of obtaining a 2Dimage of the substrate; a step S300 of deriving one region among aplurality of regions of the substrate based on the 2D image; a step S400of radiating laser light onto the one region and obtaining opticalinterference data generated from the one region; and/or a step S500 ofderiving a thickness of the coated film of the one region based on theoptical interference data.

In step S100, the first light source 130 of the inspection apparatus 10may radiate the ultraviolet light onto the coated film of the substrate2, the coated film being mixed with the fluorescent pigments. In stepS200, the first light detector 140 of the inspection apparatus 10 maycapture fluorescence generated from the coated film onto which theultraviolet light is radiated, and may obtain a 2D image of thesubstrate. In step S300, the processor 110 of the inspection apparatus10 may derive one region among the plurality of regions of the substratebased on the 2D image. In step S400, the second light source 150 mayradiate the laser light onto the derived one region, and the secondlight detector 160 may obtain optical interference data (e.g., the firstoptical interference data or the like) generated from the one region, bythe laser light. Here, the optical interference data may be associatedwith the interference light of the reference light and the measurementlight generated by the first OCT part, or the interference light of thereflected light (acting as the reference light) and the scattered light(acting as the measurement light) generated by the second OCT part. Instep S500, the processor 110 may derive the thickness of the coated filmspread on the one region of the substrate 2 based on the opticalinterference data. In the present disclosure, the amount of spread maybe derived based on the 2D image according to various embodiments. Also,the thickness may be measured using the OCT part 170 according tovarious embodiments.

According to an embodiment, step S300 of deriving the one region mayinclude an operation in which the processor 110 derives the amount ofspread of the coated film for each of the plurality of regions based onthe 2D image of the substrate 2, and/or a step in which the processor110 determines, as the above-described one region, a region of which theamount of spread is less than or equal to a predetermined amount ofspread.

According to an embodiment, step S300 of deriving the one region mayinclude a step in which the processor 110 determines the above-describedone region based on information about a region of interest set inadvance by a user.

According to an embodiment, the region of interest may be a regionincluding electrodes of elements on the substrate.

According to an embodiment, step S300 of deriving the one region mayinclude a step in which the processor 110 determines a region, which isdetermined to be a region including a defect on the substrate based onthe 2D image, as the above-described one region.

According to an embodiment, the region including the electrode may bederived by the processor 110 based on element arrangement informationindicating the arrangement of elements on the substrate.

According to an embodiment, the reflected light which is reflected fromthe surface of the coated film may be used as the reference light.According to an embodiment, the second light source 150 of the secondOCT part may radiate laser light onto the coated film of the substrate 2along a first direction. Also, the second light detector 160 of thesecond OCT part may capture the interference light that proceeds in thedirection opposite to the first direction.

According to an embodiment, the interference light may be interferencelight generated by the interference between the reflected light, whichis laser light reflected from the surface of the coated film, and thescattered light, which is laser light that penetrates the coated filmand is scattered from the boundary between the coated film and thesubstrate. The interference light may be interference light generatedfrom the above-described one region derived from among the plurality ofregions.

According to an embodiment, step S500 of deriving the thickness of thecoated film of the one region may include: a step in which the processor110 obtains a sectional image of a section cut in the first axialdirection (i.e. the z-axis direction) corresponding to the depthdirection of the coated film based on the above-described opticalinterference data (e.g., first optical interference data or the like);and/or a step in which the processor 110 determines the thickness of thecoated film spread on the above-described one region based on a boundaryline in the sectional image.

Various embodiments of the present disclosure may be implemented assoftware on a machine-readable storage medium. The software may besoftware for implementing various embodiments of the present disclosure.The software may be inferred from various embodiments of the presentdisclosure by programmers in the field of the art to which the presentdisclosure belongs. For example, the software may be a program includinginstructions (e.g., code or code segments) which are readable by adevice. The device may be a device such as a computer, which is operableaccording to instructions retrieved from a storage medium. According toan embodiment, the device may be the inspection apparatus 10 accordingto embodiments of the present disclosure. According to an embodiment, aprocessor of the device may execute retrieved instructions, such thatthe elements of the device perform functions corresponding to theinstructions. According to an embodiment, the processor may be theprocessor 110 according to embodiments of the present disclosure. Thestorage medium may indicate all types of recording media storing datawhich are readable by a device. The storage medium may include, forexample, ROM, RAM, a CD-ROM, magnetic tape, a floppy disk, an opticaldata storage device, or the like. According to an embodiment, thestorage medium may be the memory 120. According to an embodiment, thestorage medium may be implemented to be distributed in computer systemsor the like connected via a network. The software may be storeddistributedly on a computer system or the like, and may be executed. Thestorage medium may be a non-transitory storage medium. Thenon-transitory storage medium indicates a tangible medium that existsirrespectively of semi-permanent or temporary storage of data, and doesnot include a signal that is propagated in a transient manner.

According to the various embodiments of the present disclosure, asubstrate inspection apparatus can accurately measure the thickness of acoated film even when the coated film is as thin as a predeterminedthickness (e.g., 30 μm) or less.

According to the various embodiments of the present disclosure, thesubstrate inspection apparatus can shorten the amount of time spentmeasuring the thickness of a coated film of the entire substrate bysampling a predetermined region.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the embodiments described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the embodiments describedherein may be made without departing from the spirit of the disclosures.The accompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thedisclosures.

What is claimed is:
 1. A substrate inspection apparatus comprising: afirst light source configured to radiate an ultraviolet light onto acoated film of a substrate, the coated film being mixed with fluorescentpigments; a first light detector configured to capture fluorescencegenerated from the coated film onto which the ultraviolet light isradiated, and to obtain a two-dimensional (2D) image of the substrate; amemory (120) configured to store information indicating a predeterminedregion of interest on the substrate; a processor configured to determinea first region among a plurality of regions of the substrate based onthe 2D image and the information indicating the region of interest; asecond light source configured to radiate a laser light onto the firstregion; and a second light detector configured to obtain opticalinterference data generated from the first region by the laser light,wherein the processor is configured to derive a thickness of the coatedfilm of the first region based on the optical interference data.
 2. Thesubstrate inspection apparatus of claim 1, wherein the processor isconfigured to: derive an amount of spread of the coated film for each ofthe plurality of regions based on the 2D image; and determine a secondregion among the plurality of regions, wherein an amount of spread ofthe second region is less than or equal to a predetermined amount, andwherein the second light source radiates a laser light onto the secondregion, the second light detector obtains optical interference datagenerated from the second region, and the processor derives a thicknessof the coated film of the second region based on the opticalinterference data from the second region.
 3. The substrate inspectionapparatus of claim 1, wherein the processor is configured to determine athird region among the plurality of regions, the third region includinga defect on the substrate based on the 2D image, and wherein the secondlight source radiates a laser light onto the third region, the secondlight detector obtains optical interference data generated from thethird region, and the processor derives a thickness of the coated filmof the third region based on the optical interference data from thethird region.
 4. The substrate inspection apparatus of claim 1, whereinthe memory is further configured to store element arrangementinformation indicating arrangement of elements on the substrate, whereinthe processor is further configured to determine a fourth regionincluding electrodes of the elements among the plurality of regions bycomparing the element arrangement information with the 2D image, andwherein the second light source radiates a laser light onto the fourthregion, the second light detector obtains optical interference datagenerated from the fourth region, and the processor derives a thicknessof the coated film of the fourth region based on the opticalinterference data from the fourth region.
 5. The substrate inspectionapparatus of claim 1, wherein a reflected light which is reflected froma surface of the coated film is used as a reference light.
 6. Thesubstrate inspection apparatus of claim 5, wherein the processor isfurther configured to: obtain a sectional image showing a section cut ina first axial direction corresponding to a depth direction of the coatedfilm, based on the optical interference data from the first region; anddetermine the thickness of the coated film of the first region based ona boundary line in the sectional image.
 7. The substrate inspectionapparatus of claim 5, wherein a reflectivity of the surface of thecoated film with respect to the laser light is determined based on afluorescent pigment mixing ratio of the coated film with which thefluorescent pigments are mixed, and wherein the fluorescent pigmentmixing ratio is set to a value that enables the reflectivity to exceed apredetermined reference value.
 8. The substrate inspection apparatus ofclaim 5, wherein the coated film is formed of at least one materialselected from among acrylic, urethane, polyurethane, silicone, epoxy, anultraviolet (UV) curable material, and an infrared (IR) curablematerial.
 9. The substrate inspection apparatus of claim 5, wherein thesurface of the coated film is formed to be a curved surface.
 10. Asubstrate inspection method comprising: radiating an ultraviolet lightonto a coated film of a substrate, the coated film being mixed withfluorescent pigments; obtaining a 2D image of the substrate by capturingfluorescence generated from the coated film onto which the ultravioletlight is radiated; determining a first region among a plurality ofregions of the substrate based on the 2D image and informationindicating a predetermined region of interest on the substrate;radiating a laser light onto the first region and obtaining opticalinterference data generated from the first region by the laser light;and deriving a thickness of the coated film of the first region based onthe optical interference data.
 11. The substrate inspection method ofclaim 10, comprising: deriving an amount of spread of the coated filmfor each of the plurality of regions based on the 2D image; determininga second region among the plurality of regions, wherein an amount ofspread of the second region is less than or equal to a predeterminedamount; radiating a laser light onto the second region and obtainingoptical interference data generated from the second region; and derivinga thickness of the coated film of the second region based on the opticalinterference data from the second region.
 12. The substrate inspectionmethod of claim 10, comprising: determining a third region among theplurality of regions, the third region including a defect on thesubstrate based on the 2D image, and radiating a laser light onto thethird region and obtaining optical interference data generated from thethird region; and deriving a thickness of the coated film of the thirdregion based on the optical interference data from the third region. 13.The substrate inspection method of claim 10, comprising: determining afourth region including electrodes of elements on the substrate amongthe plurality of regions by comparing the 2D image with elementarrangement information indicating arrangement of the elements on thesubstrate, radiating a laser light onto the fourth region and obtainingoptical interference data generated from the fourth region; and derivinga thickness of the coated film of the fourth region based on the opticalinterference data from the fourth region.
 14. The substrate inspectionmethod of claim 10, wherein a reflected light which is reflected from asurface of the coated film is used as a reference light.
 15. Thesubstrate inspection method of claim 14, wherein the deriving thethickness of the coated film comprises: obtaining a sectional imageshowing a section cut in a first axial direction corresponding to adepth direction of the coated film, based on the optical interferencedata from the first region; and determining the thickness of the coatedfilm of the first region based on a boundary line in the sectionalimage.
 16. The substrate inspection method of claim 14, wherein areflectivity of the surface of the coated film with respect to the laserlight is determined based on a fluorescent pigment mixing ratio of thecoated film with which the fluorescent pigments are mixed; and whereinthe fluorescent pigment mixing ratio is set to a value that enables thereflectivity to exceed a predetermined reference value.
 17. Thesubstrate inspection method of claim 14, wherein the coated film isformed of at least one material selected from among acrylic, urethane,polyurethane, silicone, epoxy, an ultraviolet (UV) curable material, andan infrared (IR) curable material.
 18. The substrate inspection methodof claim 14, wherein the surface of the coated film is formed to be acurved surface.